Cold could kill some invasive insects - WCAX.COM Local Vermont News, Weather and Sports-

Cold could kill some invasive insects

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For Vermont state entomologist Alan Graham and the bugs he studies, winter is the offseason.

Time to catch up on organizing a collection of mosquitoes or to identify a bug sent in by a nervous homeowner.

"Everybody needs an entomologist," Graham said.

But this winter is no vacation for some cold-intolerant invasives. Take the hemlock woolly adelgid-- the aphid-like insects were first spotted in Windham and Bennington counties back in 2007. They suck the life out of hemlock needles, causing trees to die. But they can't survive temperatures below minus 5.

"The cold temperature is impacting populations and yes, it would set it back so our trees will maybe have enough reprieve in cold years to not have the decline that's been seen in the very southern part of our country where large mountain ranges have completely died off," Graham said.

But it won't eradicate them. Along with being highly successful at reproduction, Graham says they are also extremely adept at getting around.

"They look for different transport systems, so birds could be involved in moving insects, humans could be involved in moving insects," Graham explained.

Other invasives like the emerald ash borer, which can decimate ash trees, and the Asian longhorned beetle, which targets sugar maples, have yet to be spotted in Vermont. Both are considered more resilient to cold and therefore a threat throughout the state and further to the north.

"If the emerald ash borer gets into Vermont it has a pretty much unhindered pathway up through the forest," Graham said. "It would be a shame to lose that species."

When it comes to other potentially dangerous insects like ticks and mosquitoes that carry Eastern equine encephalitis (EEE), Graham says the cold can play a factor, but once again it's no slam dunk. The mosquito larvae winter over on tree roots, giving them some protection.

"Most areas of Vermont, the ticks are going to be insulated by the snow cover and the ticks will do quite fine," Graham said.

And with most scientists agreeing that the overall trend is toward warmer winters, all bets are off.

"If it tends toward warmer, insect ranges from the south are going to more successfully move north," Graham said.

In the short term, Graham says some of the answers will be available soon enough: "We'll have a better idea next spring."

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